Airbags for vehicle occupant restraint systems are normally made of silicone-coated or uncoated polyamide or polyester fabrics. The fabrics have to allow a specific adjustment of the air permeability and moreover, they have to be heat-resistant. Furthermore, the fabric should fold well and have the smallest possible mass since there is an interest for the airbag to occupy as little space as possible in the vehicle.
It has already been proposed to provide the inside of the airbags with heat-absorbing means such as, for example, a film coating or other sacrificial materials. These sacrificial materials are melted or degraded by the hot gases flowing into the airbag and, in this manner, are supposed to protect the actual airbag wall from damage. As an alternative, high-temperature-resistant fiber materials with higher melting points than the usual nylon fabrics are to be used. The use of sacrificial materials, however, leads to a greater layer thickness and to a higher weight of the airbag fabric. The use of special high-temperature-resistant plastics is not cost-effective.
From U.S. Pat. No. 5,599,585 there is known the production of metallized fabrics by the employment of plasma coating technology. Document JP-A-05338092 describes the plasma treatment of airbag fabrics in order to improve the adherence of a thermoplastic elastomer that is subsequently applied onto the treated fabric.
There is still a need for airbags that can be manufactured inexpensively and that have improved heat resistance.